Gasoline fuel composition

ABSTRACT

A gasoline fuel composition includes 1.0 vol % or less of benzene, 2.8 to 30.0 vol % of aromatics having a carbon number of 9, 0.5 to 3.0 vol % of aromatics having a carbon number of 10, and olefins. The olefins include a linear olefin having a terminal double bond, the liner olefin being included in a proportion of 1.0 to 2.0 vol % in the gasoline fuel composition.

TECHNICAL FIELD

The present invention relates to a gasoline fuel composition constituting gasoline fuel for use in a gasoline engine provided in an automobile or the like.

BACKGROUND ART

It is known that adhesion of a heavy fraction and olefins included in gasoline which is fuel as deposits to an intake system of a gasoline engine, particularly to an intake valve, adversely affects combustion performance, emission performance and driving performance because the optimum air-fuel ratio of the engine cannot be kept. Accordingly, adjusting the composition of gasoline fuel, in particular regular gasoline, to a composition which is unlikely to generate deposits has been attempted (e.g., Patent Literature 1). Particularly in premium gasoline, a detergent is commonly added.

The detergent has a function of removing deposits or preventing adhesion. A surfactant including such as amines or amides as an active ingredient can be used as the detergent as described in “Qualities and Standards of Petroleum Products” by Petroleum Association of Japan (N0 Patent Literature 1).

Various attempts are made to improve the cleaning performance for deposits of detergent-containing gasoline. For example, Japanese Patent Application Laid-Open No. 2006-137927 (Patent Literature 2) proposes a gasoline composition containing a friction modifier and a detergent-dispersant, the gasoline composition satisfying predetermined properties, in order to obtain the gasoline composition having high cleaning performance of intake valve deposits and high gas emission reduction effect.

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Patent No. 4856992 -   Patent Literature 2: Japanese Patent Laid-Open No. 2006-137927

Non Patent Literature

-   Non Patent Literature 1: Petroleum Association of Japan, “Qualities     and Standards of Petroleum Products” page 40, 1984

SUMMARY OF INVENTION Technical Problem

In general, a cleaning effect of the intake valve deposits by a detergent improves as the added amount of a detergent increases. However, an excessive added amount of the detergent, which is a high-molecular compound, makes nonvolatile substances in gasoline fuel oil increased, and thus an intake valve shaft sticks and deposits inside a combustion chamber (combustion chamber deposits) increase. That is rather an issue because the engine condition tends to deteriorate.

The nonvolatile substances can be evaluated by so-called “unwashed existent gum”, which is an evaporation residue before washing with heptane in determination of existent gum in fuel oil. From the viewpoint of the above-described issue, the JIS Standards about automobile gasoline (JIS K 2202) set the upper limit of unwashed existent gum as well as the upper limit of existent gum. As a result, the allowable amount of the detergent added is restricted by unwashed existent gum, and the resulting cleaning effect is also limited.

Accordingly, an object of the present invention is to provide a gasoline fuel composition having a high cleaning effect.

Solution to Problem

As a result of diligent research to achieve the above object, the present inventors found a gasoline fuel composition having a high cleaning effect. That is to say, one aspect of the present invention is a gasoline fuel composition including 1.0 vol % or less of benzene, 2.8 to 30.0 vol % of aromatics having a carbon number of 9, 0.5 to 3.0 vol % of aromatics having a carbon number of 10, and olefins, wherein the olefins include a linear olefin having a terminal double bond, the liner olefin being included in a proportion of 1.0 to 2.0 vol % in the gasoline fuel composition.

Advantageous Effects of Invention

As described above, the present invention can provide a gasoline fuel composition having a high cleaning effect.

Description of Embodiments

The gasoline fuel composition according to the present invention contains aromatics. The aromatics are included in a proportion of preferably 33.0 to 46.0 vol % and more preferably 34.0 to 46.0 vol % in the gasoline fuel composition. When the content of the aromatics is larger, an amount of deposits to be generated may increase.

The aromatics include benzene, which is one of aromatics having a carbon number of 6. The benzene is contained in a proportion of 1.0 vol % or less and preferably 0.3 to 0.8 vol % in the gasoline fuel composition. Since a large content of benzene causes air pollution, a smaller content of benzene is preferable from the viewpoint of emission control.

The aromatics include aromatics having carbon number of 9. The aromatics having carbon number of 9 are included in a proportion of 2.8 to 30.0 vol %, preferably 3.0 to 26.0 vol %, more preferably 3.0 to 23.0 vol %, and even more preferably 5.0 to 20.0 vol % in the gasoline fuel composition. A larger content of the aromatics having carbon number of 9 tends to provide greater cleaning performance but an excessively large content may cause an increase of particulate substance.

The aromatics having carbon number of 9 include monoalkylbenzenes such as i-propylbenzene and n-propylbenzene; dialkylbenzenes such as 1-methyl-2-ethylbenzene, 1-methyl-3-ethylbenzene, and 1-methyl-4-ethylbenzene; and trialkylbenzenes such as 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, and 1,3,5-trimethylbenzene. In the gasoline fuel composition, the total content of dialkylbenzenes and trialkylbenzenes having carbon number of 9 is preferably 2.0 vol % or more. Since aromatics having a plurality of alkyl groups have better oxidation stability than aromatics having monoalkylbenzenes, the former are less likely to generate deposits. Accordingly, it is preferable to increase the proportion of the aromatics having a plurality of alkyl groups.

The aromatics include aromatics having carbon number of 10. The aromatics having carbon number of 10 are included in a proportion of 0.5 to 3.0 vol %, preferably 0.5 to 2.5 vol %, and more preferably 0.5 to 2.2 vol % in the gasoline fuel composition. A larger content of the aromatics having carbon number of 10 is likely to generate deposits.

The aromatics include indanes, and examples of indanes include indane, methylindane, and climethylindane. Indanes is included in a proportion of preferably 0.4 vol % or less and more preferably 0.2 vol % or less in the gasoline fuel composition. Indanes have poor oxidation stability, and a high boiling point relative to the molecular weight, and are likely to generate deposits at the temperature around the valves.

The gasoline fuel composition according to the present invention includes olefins. The content of the olefins is preferably 10.0 to 40.0 vol % and more preferably 15.0 to 30.0 vol %. A larger content of olefins may deteriorate oxidation stability.

The olefins include a linear olefin having a terminal double bond. The linear olefin having a terminal double bond is included in a proportion of 1.0 to 2.0 vol % and preferably 1.0 to 1.5 vol % in the gasoline fuel composition. The linear olefin having a terminal double bond is, for example, an olefin having carbon number of 4 to 6. The linear olefin having a terminal double bond has a significantly high burning velocity and thus promptly combusts in the combustion chamber. Accordingly, when the olefin having a terminal double bond is present in a certain amount, the olefin can reduce unburned substances that become deposit precursors, and can prevent deposit generation. The content of the linear olefin having a terminal double bond can be adjusted by, for example, increasing a blending quantity of a catalytically cracked gasoline component or changing a blending quantity of a gasoline component in which the concentration of the linear olefin having a terminal double bond is low.

The gasoline fuel composition according to the present invention may include paraffins. The paraffins are included in an amount of preferably 10.0 to 90.0 vol % and more preferably 25.0 to 50.0 vol % in the gasoline fuel composition. Normal paraffins may be included in an amount of 3.8 to 10.0 vol % in the gasoline fuel composition. When the content of normal paraffins is smaller, emission performance may deteriorate due to low combustibility. An excessive content of normal paraffins may lower an octane number. Isoparaffins may be included in an amount of 22.0 to 50.0 vol %.

The gasoline fuel composition according to the present invention may contain naphthene. Naphthene is included in a proportion of preferably 0.5 to 4.5 vol % and more preferably 1.0 to 1.3 vol % in the gasoline fuel composition.

The gasoline fuel composition according to the present invention has a density at 15° C. of preferably 0.7000 to 0.7800 g/cm³ and more preferably 0.7100 to 0.7800 g/cm³. A larger density may cause defect in a combustion chamber in the engine due to carbon fouling of a spark plug. A smaller density may deteriorate fuel economy.

The gasoline fuel composition according to the present invention has a vapor pressure (VP) of preferably 44.0 kPa to 93.0 kPa. Since gas evaporated from the fuel causes air pollution, a smaller vapor pressure is preferable from the viewpoint of the emission control.

The gasoline fuel composition according to the present invention has an initial boiling point of, for example, 25.0 to 60.0° C. A 10% distillation temperature is preferably 30.0 to 70.0° C. When the 10% distillation temperature is excessively low, vapor lock may likely to occur. When the 10% distillation temperature is excessively high, cold startability may deteriorate. A 50% distillation temperature is preferably 45.0 to 120.0° C. When the 50% distillation temperature is excessively low, fuel economy may become worse. When the 50% distillation temperature is excessively high, acceleration performance may be poor. A 90% distillation temperature is preferably 130.0 to 185.0° C. When the 90% distillation temperature is excessively low, fuel economy become worse. When the 90% distillation temperature is excessively high, a function of lubricant is impaired due to oil dilution. An end point is preferably 180.0° C. or lower.

A component having a boiling point of 190.0° C. or higher is included in a proportion of preferably 1.7 vol % or less, and more preferably 1.0 vol % or less in the gasoline fuel composition according to the present invention. The component having a boiling point of 190.0° C. or higher stably exists as a liquid even at the temperature around the valves, which may cause deposits to generate and may prevent deposits from washing away by aromatics.

The gasoline fuel composition according to the present invention has a research octane number (RON) of preferably 89.0 or higher, more preferably 98.0 or higher, and even more preferably 100.0 or higher. A motor octane number (MON) is preferably 85.0 or higher and more preferably 87.0 or higher.

The gasoline fuel according to the present invention may include additives. The additives include such as detergents, friction modifiers, rust inhibitors, dehazer, anti-knock additives, antioxidants, metal deactivators, antistatic agents, dyes, and corrosion inhibitors. A detergent may be used to improve cleaning performance but in the case of an excessive amount of the detergent, the combustion chamber deposits increase. Additives may be included in a proportion of preferably 50 to 600 mass ppm and more preferably 250 to 450 mass ppm in the gasoline fuel composition of the present invention.

The gasoline fuel composition according to the present invention can be produced by changing the blending proportion of components selected from isomerized gasoline, light cracked gasoline, heavy cracked gasoline, alkylate, catalytically reformed gasoline, a plurality of gasoline components obtained by being separated by distillation from catalytically reformed gasoline distilled from an aromatic recovery unit, a plurality of gasoline components being removed aromatics such as benzene through solvent extraction of the aforementioned gasoline components using sulfolane or the like, light naphtha, and butane fraction, or can be produced by adjusting operational conditions, such as a cut points and a yield from a distillator, a reaction temperature of a reactor, and an extraction temperature and a solvent ratio of an extractor, when obtaining the respective components.

EXAMPLES Examples 1 to 5 and Comparative Examples 1 to 5

The gasoline fuel compositions of Examples 1 to 5 and Comparative Examples 1 to 5 were obtained by blending two or more components selected from butane, isomerate, alkylate, light naphtha, toluene distilled from a sulfolane extractor, toluenes distilled from an aromatic recovery unit, aromatics including a large amount of aromatics having carbon number of 9 or more, light cracked gasoline including a large amount of linear olefin having a terminal double bond, and heavy cracked gasoline. As additives, the same amount of a PEA/PIBA detergent was added in Examples 1 to 4 and Comparative Examples 1 to 5, and a PEA detergent and a friction modifier were added in Example 5. The cleaning performance of the gasoline fuel compositions of Examples 1 to 5 and Comparative Examples 1 to 5 was measured as follows. The results are shown in Table 3 and Table 4. The content of the linear olefin having a terminal double bond in the gasoline fuel compositions of Examples 1 to 5 and Comparative Examples 1 to 5 is shown in Table 1 and Table 2. Properties and the like in Table 1 to 4 were measured as follows.

Density (15° C.):

Measured in accordance with JIS K 2249-1 “Crude petroleum and petroleum products—Determination of density—Part 1: Oscillating U-tube method”.

Vapor Pressure (VP) (kPa):

Measured in accordance with JIS K 2258-2 “Crude petroleum and petroleum products—Determination of vapor pressure—Part 2: Triple expansion method”.

ASTM Distillation (Distillation):

Measured in accordance with JIS K 2254 “Petroleum products—Determination of distillation characteristics 4. Normal pressure distillation test method”.

Composition:

Measured in accordance with JIS K 2536-2 “Liquid petroleum products—Testing method of components Part 2: Determination of total components by gas chromatography”.

Boiling Point 190.0° C.:

Calculated from the amount of the evaporation at 190.0° C. or higher based on a distillation curve in accordance with JIS K 2254 “Petroleum products—Determination of distillation characteristics 4. Normal pressure distillation test method”.

Cleaning Performance (Clean-Up Rate):

The evaluation method is as follows.

-   Test environment temperature; 25 degrees C. -   Sample of engine; 1.5 L in-line four cylinder naturally aspirated     engine

Test Method;

-   1) Weight A of brand-new intake valves was measured, and the engine     was assembled therewith. -   2) One set of engine operation consisting of “a rotational speed of     2,000 r/min for 75 seconds and a rotational speed of 3,800 r/min for     225 seconds” was repeated to operate the engine for 100 hours in     total. Then, the engine was disassembled, and total weight B of the     intake valves and intake valve deposits was measured. A fuel     corresponding to regular gasoline was used at this time. -   3) The engine was assembled with the intake valves after the weight     was measured, and the engine was operated for 100 hours according to     the operational program mentioned in 2) using the fuel compositions     of the Examples and Comparative Examples. Then, the engine was     disassembled, and total weight C of the intake valves and intake     valve deposits was measured. -   4) The change rate of the weight of intake valve deposits between     the engine tests 2) and 3), i.e., (((B-A)−(C-A))/(B-A)×100), was     regarded as the deposit removal rate (clean-up rate).

Content of Linear Olefin Having a Terminal Double Bond:

Measured in accordance with JIS K 2536-2 “Liquid petroleum products—Testing method of components Part 2: Determination of total components by gas chromatography”.

TABLE 1 Example No. 1 2 3 4 5 C4 Vol % 0.70 0.05 0.17 0.07 0.07 C5 Vol % 0.27 0.69 1.09 0.94 0.94 C6 Vol % 0.08 0.22 0.22 0.33 0.33 C7 Vol % — — — — — C8 Vol % — — — — — C9 Vol % — — — — — C10 Vol % — — — — — C11 Vol % — — — 0.01 0.01 Total Vol % 1.1 1.0 1.5 1.4 1.4 —: Not detected Cn: Indicates a linear olefin, which has n carbon atoms, having a terminal double bond

TABLE 2 Comparative Example No. 1 2 3 4 5 C4 Vol % — — 0.02 0.04 0.02 C5 Vol % 0.00 — 0.64 1.45 0.59 C6 Vol % — 0.00 0.22 0.50 0.20 C7 Vol % — — — — — C8 Vol % — — — — — C9 Vol % 0.00 0.00 0.00 — — C10 Vol % — — — — — C11 Vol % 0.06 0.02 0.04 0.01 — Total Vol % 0.1 0.0 0.9 2.0 0.8 —: Not detected Cn: Indicates a linear olefin, which has n carbon atoms, having a terminal double bond

TABLE 3 Example No. 1 2 3 4 5 Density @15° C. [g/cm³] 0.7499 0.7526 0.7696 0.7424 0.7424 Vapor Pressure: VP [kPa] 88.1 58.9 54.1 58.4 58.4 Distillation IBP ° C. 26.5 37.0 34.5 32.0 32.0 10 ° C. 40.5 53.0 53.5 54.0 54.0 50 ° C. 90.0 80.5 102.5 93.0 93.0 90 ° C. 164.0 132.0 148.5 142.5 142.5 FBP ° C. 178.0 179.5 175.5 176.5 176.5 Recovery [vol %] 97.0 98.5 98.5 98.0 98.0 Residue [vol %] 1.0 1.0 1.0 1.0 1.0 Loss [vol %] 2.0 0.5 0.5 1.0 1.0 Compositions (GC) n-Paraffins [vol %] 7.0 3.8 3.9 6.7 6.7 i-Paraffins [vol %] 28.9 23.4 22.7 41.1 41.1 Olefins [vol %] 20.2 28.6 19.9 16.7 16.7 Naphthene [vol %] 4.1 3.0 3.4 1.3 1.3 Aromatics [vol %] 39.8 41.3 45.6 34.2 34.2 C6 Aromatics [vol %] 0.6 0.8 0.6 0.6 0.6 C9+ Aromatics [vol %] 28.5 10.3 11.8 11.7 11.7 Oxygen [vol %] 0.0 0.0 4.5 0.0 0.0 RON 98.2 100.3 98.4 100.3 100.3 MON 85.4 89.0 86.8 88.2 88.2 b.p ≥190.0° C. [vol %] 0.9 0.0 0.6 0.9 0.9 C9 Aromatics [vol %] 25.5 9.6 10.2 9.4 9.4 mono- [vol %] 1.7 0.7 0.7 0.8 0.8 di- [vol %] 9.7 3.8 4.1 3.9 3.9 tri- [vol %] 14.1 5.1 5.4 4.7 4.7 C10 Aromatics [vol %] 2.5 0.6 1.3 2.2 2.2 Total Indans [vol %] 0.4 0.1 0.2 0.2 0.2 (Total Indans) + [vol %] 2.9 0.7 1.6 2.4 2.4 (C10+ Aromatics) Clean-up rate [%] 56.5 55.0 55.0 54.5 61.0

TABLE 4 Comparative Example No. 1 2 3 4 5 Density @15° C. [g/cm³] 0.7037 0.7670 0.6937 0.7675 0.7430 Vapor Pressure: VP [kPa] 68.6 90.3 93.3 51.8 61.7 Distillation IBP ° C. 30.5 29.5 27.5 38.0 30.0 10 ° C. 64.5 53.5 44.5 54.5 55.0 50 ° C. 104.5 115.0 93.5 100.5 101.0 90 ° C. 137.0 165.5 130.0 165.0 112.5 FBP ° C. 199.5 190.5 195.0 180.5 134.5 Recovery [vol %] 96.5 94.5 95.0 98.5 97.5 Residue [vol %] 1.0 1.0 1.0 1.0 1.0 Loss [vol %] 2.5 4.5 4.0 0.5 1.5 Compositions (GC) n-Paraffins [vol %] 6.3 15.1 8.5 3.2 10.1 i-Paraffins [vol %] 80.9 31.2 68.6 24.0 44.6 Olefins [vol %] 1.4 0.9 11.5 24.0 10.5 (Di-olefins) [vol %] 0.0 0.0 0.0 0.0 0.2 Naphthene [vol %] 0.6 0.3 0.9 1.4 1.1 Aromatics [vol %] 5.0 46.7 4.6 47.4 33.2 (C6 Aromatics) [vol %] 0.0 0.1 0.2 0.6 0.5 (C9+ Aromatics) [vol %] 4.9 26.5 4.3 26.6 0.9 Oxygen [vol %] 5.9 5.9 5.8 0.0 0.5 RON 103.6 100.8 101.7 101.2 100.4 MON 96.1 91.0 93.5 88.2 88.8 b.p ≥190.0° C. [vol %] 1.9 1.7 1.5 1.4 0.7 C9 Aromatics [vol %] 2.8 22.8 2.6 23.0 0.3 mono- [vol %] 0.2 1.7 0.2 1.7 0.0 di- [vol %] 1.1 8.9 1.0 9.0 0.1 tri- [vol %] 1.5 12.2 1.4 12.3 0.2 C10 Aromatics [vol %] 1.9 3.3 1.5 3.2 0.5 Total Indans [vol %] 0.1 0.4 0.1 0.4 0.1 (Total Indans) + (C10+ [vol %] 2.2 3.7 1.7 3.6 0.6 Aromatics) Clean-up rate [%] 35.0 43.0 30.0 44.0 46.0 

What is claimed is:
 1. A gasoline fuel composition comprising 1.0 vol % or less of benzene, 2.8 to 30.0 vol % of aromatics having a carbon number of 9, 0.5 to 3.0 vol % of aromatics having a carbon number of 10, and olefins, wherein the olefins include a linear olefin having a terminal double bond, the liner olefin being included in a proportion of 1.0 to 2.0 vol % in the gasoline fuel composition.
 2. The gasoline fuel composition according to claim 1, wherein the linear olefin is included in a proportion of 1.0 to 1.5 vol % in the gasoline fuel composition.
 3. The gasoline fuel composition according to claim 1, wherein the olefins are included in a proportion of 10.0 to 40.0 vol %.
 4. The gasoline fuel composition according to claim 1, including 1.7 vol % or less of a component having a boiling point of 190.0° C. or higher. 